1. Technical Field
The present invention relates to a test apparatus.
2. Related Art
A device using an element such as an IGBT is known to be used as a switching device in a large-current circuit. In this device, a plurality of IGBT elements are formed in parallel, according to the desired current specifications, as described in Patent Document 1, for example. A test apparatus that tests the device supplies power from a common power supply to the plurality of IGBTs.    Patent Document 1: Japanese Patent Application Publication No. 2000-58820
One type of test for a large-current switching device is a withstand voltage test that involves applying a high voltage to the device, such as in an avalanche test. However, if there is variation in the characteristics of the elements provided in parallel in the device, the current is focused in a portion of the elements, which can damage the elements. Since a plurality of elements are formed on a common substrate, if a portion of the elements are damaged and heat is generated due to excessive current flowing therethrough, the heat is spread to other elements. As a result, the other elements are also damaged. When this damage spreads, the elements in the device are damaged in a manner similar to an avalanche.
One method used to prevent this type of damage to the elements involves forming in the test apparatus a cutoff circuit that cuts off the power supply when a prescribed current value is detected. However, it is necessary to determine, for each device and each type of test, under what conditions the power should be cut off. Therefore, it is necessary to form a cutoff circuit for each cutoff condition.